Synonyms of 'ago'
in the pastHe arrived here a few days ago.
Although since can be used as a synonym of ago in certain contexts, the use of ago and since together, as in it's ten years ago since he wrote that novel, is redundant. Instead, it would be correct to use it is ten years since he wrote that novel, or it is ten years ago that he wrote that novel.
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in the sense of back
They had a big lottery win a few years back.
in the sense of before
The war had ended only a month or so before.
Video: pronunciation of 'ago'
Thesaurus for ago from the Collins English Thesaurus